Faculty Bibliography

OBJECTIVE:To determine the frequency of magnetic resonance imaging (MRI) findings of ischiofemoral impingement (IFI) in patients with inflammatory myositis (IM) and associated factors. METHODS:Pelvis and thigh MRI studies of 314 consecutive patients (57% women; mean age, 55.5 years; range, 18-85) with suspected muscle disease were reviewed. RESULTS:Ischiofemoral impingement at MRI was present in 11% of patients with a final diagnosis of IM and in 2% of patients with an alternative diagnosis (P = 0.008). In multiple logistic regression analysis, IM, but not age or sex, was independently associated with IFI at MRI (odds ratio, 5.18; 95% confidence interval, 1.19-22.6; P = 0.028). Fatty atrophy of hip stabilizing muscles was independently associated with IFI at MRI (odds ratio per unit increase of fatty atrophy score, 1.03; 95% confidence interval, 1.01-1.05; P = 0.0007). CONCLUSIONS:Magnetic resonance imaging findings of IFI are present in 11% of IM patients and are independently associated with fatty atrophy of hip stabilizing muscles.

OBJECTIVE:The aim of this study was to test the hypothesis that a novel frequency selective nonlinear blending (NLB) algorithm increases the delineation of pulmonary embolism and venous thrombosis in portal-venous phase whole-body staging computed tomography (CT). MATERIALS AND METHODS:A cohort of 67 patients with incidental pulmonary embolism and/or venous thrombosis in contrast-enhanced oncological staging CT were retrospectively selected. Computed tomography data sets were acquired 65 to 90 seconds after intravenous iodine contrast administration using state-of-the-art multi-detector CT scanners. A novel frequency selective NLB postprocessing technique was applied to reconstructed standard CT images. Two readers determined the most suitable settings to increase the delineation of pulmonary embolism and venous thrombosis. Outcome measure included region of interest and contrast-to-noise ratio (CNR) analyses, image noise, overall image quality, subjective delineation, as well as number and size of emboli and thrombi. Statistical testing included quantitative comparisons of Hounsfield units of thrombus and vessel, image noise and related CNR values and subjective image analyses of image noise, image quality and thrombus delineation, number and size in standard, and NLB images. RESULTS:Using frequency selective NLB settings with a center of 100 HU, delta of 40 HU, and a slope of 5, CNR values of pulmonary embolism (StandardCNR, 10 [6, 16]; NLBCNR, 22 [15, 30]; P < 0.001) and venous thrombosis (StandardCNR, 8 [5, 15]; NLBCNR, 12 [7, 19]; P = 0.0007) increased. Mean vascular enhancement using NLB was significantly higher than in standard images for pulmonary arteries (Standard, 138 [118, 191] HU; NLB, 269 [176, 329] HU; P < 0.0001) and veins (Standard, 120 [103, 162] HU; NLB, 169 [132, 217] HU; P < 0.0001), respectively. Image noise was not significantly different between standard and NLB images (P = 0.64-0.88). There was substantial to almost perfect interrater agreement as well as a significant increase of overall image quality (P < 0.004) and subjective delineation of the thrombotic material (P < 0.0001) in both subgroups. Nonlinear blending images revealed 8 additional segmental and 13 subsegmental emboli. Thrombus sizes were not significantly different, but subjective accuracy of the measurement could be significantly increased using NLB (P = 0.03). CONCLUSIONS:Postprocessing of standard whole-body staging CT images with frequency selective NLB improves image quality and the delineation of pulmonary embolism and venous thrombosis.

PURPOSE/OBJECTIVE:To evaluate the diagnostic performance of a novel CT post-processing software that generates subtraction maps of baseline and follow-up CT examinations in the course of myeloma bone lesions. MATERIALS AND METHODS/METHODS:This study included 61 consecutive myeloma patients who underwent repeated whole-body reduced-dose MDCT at our institution between November 2013 and June 2015. CT subtraction maps classified a progressive disease (PD) vs. stable disease (SD)/remission. Bone subtraction maps (BSMs) only and in combination with 1-mm (BSM+) source images were compared with 5-mm axial/MPR scans. RESULTS:Haematological response categories at follow-up were: complete remission (n = 9), very good partial remission (n = 2), partial remission (n = 17) and SDh (n = 19) vs. PDh (n = 14). Five-millimetre CT scan yielded PD (n = 14) and SD/remission (n = 47) whereas bone subtraction + 1-mm axial scans (BSM+) reading resulted in PD (n = 18) and SD/remission (n = 43). Sensitivity/ specificity/accuracy for 5-mm/1-mm/BSM(alone)/BSM + in "lesion-by-lesion" reading was 89.4 %/98.9 %/98.3 %/ 99.5 %; 69.1 %/96.9 %/72 %/92.1 % and 83.8 %/98.4 %/92.1 %/98.3 %, respectively. The use of BSM+ resulted in a change of response classification in 9.8 % patients (n = 6) from SD to PD. CONCLUSION/CONCLUSIONS:BSM reading is more accurate for monitoring myeloma compared to axial scans whereas BSM+ yields similar results with 1-mm reading (gold standard) but by significantly reduced reading time. KEY POINTS/CONCLUSIONS:• CT evaluation of myeloma bone disease using a longitudinal bone subtraction post-processing algorithm. • Bone subtraction post-processing algorithm is more accurate for assessment of therapy. • Bone subtraction allowed improved and more efficient detection of myeloma bone lesions. • Post-processing tool demonstrating a change in response classification in 9.8 % patients (all showing PD). • Reading time could be substantially shortened as compared to regular CT assessment.

OBJECTIVE:The aim of this study was to optimize computed tomography (CT) surveillance of skeletal metastases in patients with breast cancer through the use of osseous subtraction maps between baseline and follow-up examinations created by a novel software algorithm. The new postprocessing algorithm segments the original bone followed by image intensity-based rigid alignment creating gray-shaded maps that highlight focal or diffuse loss or increase in bone attenuation. MATERIALS AND METHODS:Institutional review board was obtained for this retrospective data evaluation. A total of 33 consecutive patients (31 female; 2 male; mean age, 59.13 ± 12.68 years; range, 32-81 years) with breast cancer were included, who underwent 143 standardized baseline and follow-up CT examinations between February 2014 and June 2016. We classified bone metastases into lytic, sclerotic, and mixed osseous lesions. Any new osteolysis inside a known sclerotic lesion and enlargement of pre-existing sclerotic lesions were considered to represent progressive disease (PD), whereas no change was classified as stable disease (SD). Results were compared additionally with the course of the disease considering the entire skeleton and other involved organs. Software-created automated bone subtraction maps were compared with conventional CT interpretations of axial 5-mm and coronal 1-mm reformatted images. Region of interest measurements were used to quantify new lesions. Results were validated by clinical and CT follow-up. Reading time was evaluated. RESULTS:Skeletal metastases were present in 17/33 (51%) patients (9 sclerotic, 2 lytic, 6 mixed) at baseline. The use of bone subtraction maps resulted in an overall change of response classification into PD in 9/33 (8.1%) patients. Compared with conventional CT evaluation, the bone subtraction maps disclosed 123 new or enlarging sclerotic and 32 new lytic metastases in 23/33 (30.9%) examinations. Mean attenuation of new bone lesions (sclerotic or lytic) significantly increased or decreased (P < 0.01) in all patients. Bone attenuation in pelvic areas without evident metastatic disease significantly increased in patients with PD (P = 0.019), whereas there was no change in SD (P = 0.076). Lesion-based sensitivity, specificity, accuracy, positive predictive values, and negative predictive values were 98.7%, 79.5%, 94.5%, 95.1%, and 94.5%, respectively. Interobserver agreement was good (κ = 0.80; P = 0.077). Reading time was significantly faster for the bone subtraction maps versus 5-mm axial images (P < 0.001). CONCLUSIONS:Longitudinal bone subtraction maps increase the accuracy and efficiency of CT diagnosis of skeletal metastases in patients with breast cancer.

OBJECTIVES/OBJECTIVE:To test the hypothesis that a fourfold CAIPIRINHA accelerated, 10-min, high-resolution, isotropic 3D TSE MRI prototype protocol of the ankle derives equal or better quality than a 20-min 2D TSE standard protocol. METHODS:Following internal review board approval and informed consent, 3-Tesla MRI of the ankle was obtained in 24 asymptomatic subjects including 10-min 3D CAIPIRINHA SPACE TSE prototype and 20-min 2D TSE standard protocols. Outcome variables included image quality and visibility of anatomical structures using 5-point Likert scales. Non-parametric statistical testing was used. P values ≤0.001 were considered significant. RESULTS:Edge sharpness, contrast resolution, uniformity, noise, fat suppression and magic angle effects were without statistical difference on 2D and 3D TSE images (p > 0.035). Fluid was mildly brighter on intermediate-weighted 2D images (p < 0.001), whereas 3D images had substantially less partial volume, chemical shift and no pulsatile-flow artifacts (p < 0.001). Oblique and curved planar 3D images resulted in mildly-to-substantially improved visualization of joints, spring, bifurcate, syndesmotic, collateral and sinus tarsi ligaments, and tendons (p < 0.001, respectively). CONCLUSIONS:3D TSE MRI with CAIPIRINHA acceleration enables high-spatial resolution oblique and curved planar MRI of the ankle and visualization of ligaments, tendons and joints equally well or better than a more time-consuming anisotropic 2D TSE MRI. KEY POINTS/CONCLUSIONS:• High-resolution 3D TSE MRI improves visualization of ankle structures. • Limitations of current 3D TSE MRI include long scan times. • 3D CAIPIRINHA SPACE allows now a fourfold-accelerated data acquisition. • 3D CAIPIRINHA SPACE enables high-spatial-resolution ankle MRI within 10 min. • 10-min 3D CAIPIRINHA SPACE produces equal-or-better quality than 20-min 2D TSE.

RATIONALE AND OBJECTIVES:The study aimed to assess the diagnostic benefit of a novel computed tomography (CT) post-processing software generating subtraction maps of longitudinal non-enhanced CT examinations for monitoring the course of myeloma bone disease in the spine. MATERIALS AND METHODS:The local institutional review board approved the retrospective data evaluation. Included were 82 consecutive myeloma patients (46 male; mean age, 65.08 ± 9.76) who underwent 188 repeated whole-body reduced-dose Multislice Detector Computed Tomography (MDCT) at our institution between December 2013 and January 2016. Lytic bone lesions were categorized as new or enlarging versus stable. Bone subtraction maps were read in combination with corresponding 1-mm source images comparing results to those of standard image reading of 5-mm axial and 2-mm multiplanar reformat reconstructions (MPR) scans and hematologic markers, and classified as either progressive disease (PD) or stable disease (SD or remission). The standard of reference was 1-mm axial CT image reading + hematologic response both confirmed at follow-up. For statistical purposes, we subgrouped the hematologic response categories similarly to those applied for CT imaging (progression vs stable/response). RESULTS:According to the standard of reference, 16 patients experienced PD and 66 SD at follow-up. Th sensitivity, specificity, and accuracy for axial 5 mm + 2 mm MPR image versus bone subtraction maps in a "lesion-by-lesion" reading were 97.6%, 92.3%, and 97.2% versus 97.8%, 96.7%, and 97.7%, respectively. The use of bone subtraction maps resulted in a change of response classification in 9.7% of the patients (n = 8) versus 5 mm + 2 mm MPR image reading from SD to PD. Bone sclerosis lesions were detected in 52 out of 82 patients (63.4%). The reading time was significantly lower with the software bone subtraction compared to standard reading (P < 0.01) and 1-mm image reading (P < 0.001). CONCLUSION:Accuracy of bone subtraction maps reading for monitoring multiple myeloma is slightly increased over that of conventional axial + MPR image reading and significantly speeds up the reading time.

Neuropathy of the posterior femoral cutaneous nerve may manifest as pain and paresthesia in the skin over the inferior buttocks, posterior thigh, and popliteal region. Current treatment options include physical and oral pain therapy, perineural injections, and surgical neurectomy. Perineural steroid injections may provide short-term pain relief; however, to our knowledge, there is currently no minimally invasive denervation procedure for sustained pain relief that could serve as an alternative to surgical neurectomy. Percutaneous cryoablation of nerves is a minimally invasive technique that induces a sustained nerve conduction block through temporary freezing of the neural layers. It can result in long-lasting pain relief, but has not been described for the treatment of neuropathy-mediated PFCN pain. We report a technique of MR-guided cryoablation of the posterior femoral cutaneous nerve resulting in successful treatment of PFCN-mediated sitting pain. Cryoablation of the posterior femoral cutaneous nerve seems a promising, minimally invasive treatment option that deserves further investigation.

CASE DESCRIPTION A 9-year-old spayed female Rottweiler with hind limb ataxia was examined because of anorexia and an acute onset of hind limb paresis. CLINICAL FINDINGS Neurologic evaluation revealed hind limb ataxia and symmetric paraparesis with bilaterally abnormal hind limb postural reactions including hopping, hemiwalking, hemistanding, and delayed proprioception, which were suggestive of a lesion somewhere in the T3-L3 segment of the spinal cord. Thoracolumbar radiography revealed an abnormal radiopacity suggestive of a mass at T11. Two 3.5-cm-long osseous core biopsy specimens of the mass were obtained by MRI guidance. Histologic appearance of the specimens was consistent with osteosarcoma. TREATMENT AND OUTCOME The owners of the dog declined further treatment owing to a poor prognosis. The dog was euthanized within 12 months after diagnosis because of a declining quality of life. CLINICAL RELEVANCE The acquisition of biopsy specimens by MRI guidance is an emerging technique in veterinary medicine. As evidenced by the dog of this report, MRI-guided biopsy can be used to safely obtain diagnostic biopsy specimens from tissues at anatomic locations that are difficult to access. This technique can potentially be used to facilitate early diagnosis and treatment of disease, which could improve patient outcome. The MRI guidance technique described may also be useful for local administration of chemotherapeutics or radiofrequency ablation or cryoablation of various neoplasms of the vertebral column.

OBJECTIVE:To assess the quality and accuracy of metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) for the diagnosis of lumbosacral neuropathies in patients with metallic implants in the pelvis. MATERIALS AND METHODS/METHODS:Twenty-two subjects with lumbosacral neuropathy following pelvic instrumentation underwent 1.5-T MARS MRI including optimized axial intermediate-weighted and STIR turbo spin echo sequences extending from L5 to the ischial tuberosity. Two readers graded the visibility of the lumbosacral trunk, sciatic, femoral, lateral femoral cutaneous, and obturator nerves and the nerve signal intensity of nerve, architecture, caliber, course, continuity, and skeletal muscle denervation. Clinical examination and electrodiagnostic studies were used as the standard of reference. Descriptive, agreement, and diagnostic performance statistics were applied. RESULTS:Lumbosacral plexus visibility on MARS MRI was good (4) or very good (3) in 92% of cases with 81% exact agreement and a Kendall's W coefficient of 0.811. The obturator nerve at the obturator foramen and the sciatic nerve posterior to the acetabulum had the lowest visibility, with good or very good ratings in only 61% and 77% of cases respectively. The reader agreement for nerve abnormalities on MARS MRI was excellent, ranging from 95.5 to 100%. MARS MRI achieved a sensitivity of 86%, specificity of 67%, positive predictive value of 95%, and negative predictive value of 40%, and accuracy of 83% for the detection of neuropathy. CONCLUSION/CONCLUSIONS:MARS MRI yields high image quality and diagnostic accuracy for the assessment of lumbosacral neuropathies in patients with metallic implants of the pelvis and hips.